The book provides extensive details on all four Mystery Cult Houses. Each House has its own chapter, that describes the House's history and outlook as well as its magical practices and secrets. The domus magna of each House is described, as is the primus and his policies.

The book was published before The Mysteries Revised Edition, but functions best alongside it. TMRE presents further details on initiation rules, and provides complementary Mysteries occasionally alluded to as options in HoHMC.

An extensive treatment of the House's inner Mysteries and cult structure and philosophy is necessary for a portrayal of a Mystery Cult House, and for playing a magus belonging to one. This book provides the House's canonical description, adding details on sub-divisions and schools of thought within the Houses that can be of great aid to the player and inner Mysteries and initiation paths for him to aspire to.

From a storyguide's perspective, the extended descriptions provide many social groups with diverse goals and exotic, non-Hermetic, means at their disposal, which are an excellent fodder for story ideas. The book also introduces concepts like the Great Beasts, Automata, and the Axis Magica, that can also serve to drive plots.

The non-Hermetic magic and strange philosophies of the Mystery Cult Houses can add greatly to the diversity of the saga. This book will help portray the Mystery Cult Houses as more different, varied, and non-Hermetic - not just Hermetic magi separated from the rest by a single Outer Mystery virtue.

If there is a player character from one of these Houses, or if the storyguide wants to dip into them and their strange magic for story ideas or simply for a more varied description of the Order, then you should definitely pick up this book.

Perhaps the most discussed issue in relation to this book was its unique take on House Criamon, which seems to elicit a hate-it-or-love-it response. It presents a specific interpretation of what the Enigma is, and has been criticized as overly restricting Criamon character concepts. On the other hand, it has also been praised for providing a unique and original philosophy and concepts that serve as tools for portraying truly alien-thinking Criamon magi.